Mitotic index and chromosomal changes in Allium cepa as affected by an organophosphate pesticide, malathion
1999
Santiago, F.I. | Cannen, R.E.L. (De La Salle Univ., 2401 Taft Avenue, Manila (Philippines). Biology Dept.)
The cytogenetic effects of malathion, an organophosphate pesticide were investigated in A. cepa, commonly known as onion. Root tips of Allium cepa were exposed to 2850 mg/L malathion for 24 and 48 hours. The root tips were fixed, stained, squashed, examined and scored using a compound microscope. Mitotic index and chromosomal aberrations were determined. The mitotic index of root tip cells exposed to malathion was significantly decreased compared to the control. Cells exposed to malathion after 48 h had a mitotic index of 17.50 percent while the control groups had a mitotic index of 56.96 percent. A number of chromosomal aberrations were observed. Chromosomal stickiness was the most common. After 24-h exposure, 11.9 percent of the cells showed stickiness while 11.2 percent were observed after 48 h. Other aberrations include laggards, anaphase bridges and forward chromosomes. After the cells were exposed to malathion for 24 h, 5.3 percent laggards were observed, whereas 3.7 laggards were noted after 48 h. After 24-h exposure, 2.1 percent of the cells exhibited anaphase bridges while 2.9 percent had anaphase bridges after 48 h. Forward chromosomes were found in 1.7 percent of the cells exposed for 24 h while 3.1 percent of the cells exhibited this aberration after the 48-h exposure to malathion. A decreased mitotic index and a number of chromosomal aberrations were the observed effects of malathion on the root tip cells of A. cepa
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